The invention relates to aluminum titanate ceramic bodies having low thermal expansion, high porosity, and high strength and methods for manufacturing the same. Particularly, the present invention relates to aluminum titanate ceramic bodies and methods of manufacturing same wherein the body and method uses a sintering additive which aids in reducing the firing temperature and allowing for a wide range of firing temperature.
Recently, aluminum titanate (AT) based ceramic materials have been proposed, in patent applications U.S. application Ser. Nos. 10/626,317 (U.S. Publication No. 2004/0092381 now U.S. Pat. No. 7,001,861) and 60/517,348 (now U.S. application Ser. No. 10/955,364 now U.S. Pat. No. 6,942,713) and in U.S. Pat. No. 6,620,751 as an alternative for cordierite and silicon carbide (SiC) for high temperature applications, such as automotive emissions control applications.
Diesel particulate filters (DPFs) require a combination of low coefficient of thermal expansion (CTE) (for thermal shock resistance), high porosity and good pore interconnectivity (for low pressure drop and engine efficiency), and high strength (to survive handling, canning, and vibration in use).
To obtain aluminum titanate-based DPFs exhibiting the aforementioned properties it is required to fire the structures at high temperatures, generally above 1500° C., in order to achieve sufficient grain growth to produce the microcracking required for low thermal expansion. The high firing temperatures disadvantageously add cost to the processing of the product.
It would be desirable to manufacture aluminum titanate-based bodies for use in high temperature applications which can be fired at reduced temperatures without significantly impacting the desired properties in the final product structure. Accordingly, ceramic compositions achieving the aforementioned properties which enable lower firing temperatures are desired.